Optics is a critical tool for all sorts of biology and biosensing.  The workhorse methodology for measuring the adsorption of molecules to functionalized surfaces has historically been surface plasmon resonance, where light is bounced off of a biologically functionalized metal surface. 

With silicon photonics, it's possible to do similar measurements, but with much greater sensitivity, and with very high densities of sensors on a single, inexpensive silicon chip.  Dr. Hochberg's lab at the University of Washington worked with Dr. Cary Gunn early on to prove that this could be done; Genalyte is now shipping production tests for a variety of applications, including rapid COVID testing.

 

 More recently, SiDx spun off from Professor Daniel Ratner's lab at the University of Washington to commercialize new applications of silicon photonic biosensors.